Method of fixing pins in a matrix

ABSTRACT

A carding or a drawing machine wherein the pins are a noninterference fit within the pin holes in the cylinder or other matrix and are secured in position by an adhesive which may or may not be a thermoplastic.

United States Patent 91 Stewart et a1.

[451 May 1, 1973 METHOD OF FIXING PINS IN A MATRIX [75] Inventors: David Bruce Stewart, Newtyle, An-

gus; John Main, Kettins, Angus; Maurice Duncan, Camoustie, all of Scotland [73] Assignee: Wm. R. Stewart & Sons (Hacklemakers) Limited, Dundee, Scotland [22] Filed: Mar. 10, 1970 [21] Appl.No.: 18,095

[30] Foreign Application Priority Data Mar. 10, 1969 Great Britain ..12,478/69 [52] US. Cl. ..l56/98, 156/252, 156/289,

156/293, 156/298, l56/303.1, 156/330 [51] Int. Cl. ..B32b 35/00 [58] Field of Search ..156/245, 293, 298,

Primary ExaminerCarl D. Quarforth Assistant Examiner-Stephen J. Lechert, Jr. Attorney-Baldwin, Wight, Diller & Brown [57] ABSTRACT A carding or a drawing machine wherein the pins are a non-interference fit within the pin holes in the cylinder or other matrix and are secured in position by an adhesive which may or may not. be a thermoplastic.

6 Claims, 10 Drawing Figures Patented May 1, 1973 5 3,730,802

4 Sheets-Sheet 3 P a u n N 7 aw A Jm M MW .67 ddwm M g/M Mm a 6m [LEM/alga Patented May 1, 1973 3,730,802.

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METHOD OF FIXING PINS IN A MATRIX This invention relates to carding and drawing machines and the like and is concerned with an improved method of fixing the pins in their matrix.

It is well known that the accuracy of the position of v the pin points related to the axis of the matrix assembly and/or the relationship of the pin tip to the surface of the matrix and adjacent assemblies is of vital importance when related to the carding, fibrillating, drawing, combing and metering machines used in textiles, tobacco, plastics and other industries.

Moreover, the uniformity and hence the quality of a fibrous product is directly related to accuracy in the position of the pin tip in relation to its locus point (where applicable) as well as to the surface of the matrix.

For convenience the word pin is used in the following description, but it is understood that this relates to any form of inserted article including pins, spikes, or spurs of any cross-section or shape, as well as staples and wedge headed spikes inserted in grooves and the like.

The conventional method of retaining the pins in a matrix is to drill or make holes smaller than the diameter of pin to be inserted so that the pin is an interference fit. In practice there is always a variation in pin length and the fact that the pins are driven into their holes in the matrix by blows on the blunt end or base of each pin results in any such variation of length being reflected in the pin tip relationship to the surface of the matrix and to the locus point (where applicable).

Moreover, interference fitting of the pins in the holes build up stresses within the matrix which cause distortion. The extent of distortion varies considerably according to individual circumstances and is costly and often difficult to remove, and, in certain instances, may result in metal failure in densely pinned items such as comb circles and, in particular, fatigue in highly stressed components, e.g., faller bars.

We have now discovered that it is possible to eliminate distortion by making use of holes in the matrix which are of a size larger than that of the pins and filling the resultant gap with a fixing agent. An additional advantage is that the pins can now be introduced into the holes either point or base first. The pin filling operation is now executed in the absence of percussion such that the point of the pin can now be used as datum.

Furthermore, by regulating the amount by which the hole is larger than the pin, a controlled degree of random irregularitycan be introduced into the pattern of the pins while still retaining an accurate surface generated by the loci of the pin points as they more relative to the fibers or film. This random irregularity will help to ensure that each separate pin point will strike a fresh part of the film or mass of fibers, thus achieving an improved carding or combing action.

According to the present invention, a method of inserting pins in a matrix comprises the steps of (i) forming holes in the matrix which are a clearance fit in relation to the pins to be inserted therein; (ii) aligning the pins on insertion thereof in endwise relation so that their pointed ends are presented uniformly or to a deliberately varied pattern, and (iii) securing the pins in position when so aligned by means of a filling agent which adheres to the surface of the pin or hole or both.

Hitherto in the textile, plastic, and tobacco industries it has been the practice in rotary carding or metering machines, to attach the pins or staples to the roller or other rotating part by clothing it with a belt in which the pins are embedded. In more highly stressed applications the matrix may be in the form of wood, metal and, in particular, aluminum alloy.

According to this invention also, a carding element comprises a cylinder which may be open at each end and formed with through bores for the carding pins whereby the carding pins can be set in the bores or withdrawn therefrom by entering or removing them from the outside inwardly or from the inside outwardly, the pins, which are a clearance fit, being fixed in position in their bores with a fixing agent.

The absence of distortion and damage caused by percussion pinning greatly reduces any subsequent remedial operations and the grinding of the pin tips to produce uniformity of position of pin tip to surface of the matrix. This results in greater freedom of design and in the retention of the designed shape of the pin point.

The ability of the pin to remain in the matrix under load conditions is of prime importance and the shear strength of the fixing agent can be varied to suit design requirements. In most applications it is advantageous to be able to remove damaged and worn pins. The method of fixing of this invention also permits the pin to be removed with ease, using a predetermined force, thereby eliminating the tendency to break and/or bend pins due to the excessive grip traditional in the old method. Because of the larger hole prepared initially, the hole surface remains undamaged and of unaltered diameter, consequently allowing re-pinning with pins of the same diameter, whereas traditional methods required frequent increase of the pin diameter.

The invention is diagrammatically illustrated in the accompanying drawings, in which:

FIGS. 1 and 2 are profile explanatory views;

FIGS. 3 and 4 are views similar to those of FIGS. 1 and 2 but in which the bases of the pins do not protrude beyond the surface of the matrix;

FIG. 5 are scrap views showing the probable defects of traditional pinning together with the beneficial effect of the fixing agent in this respect;

FIG. 6 is a sectional view on an enlarged scale to show the improved contours which are now possible by building up the fixing agent at the root of the pin to produce a rounded-off rose-thorn" shape;

FIGS. 7 and 8 are further explanatory views;

FIGS. 9 and 10 are diagrammatic sectional views of carding machine rollers which have been pinned in accordance with the invention; FIG. 10 also shows the bearing mountings.

Referring to FIGS 1 and 2, M indicates a matrix in which have been inserted a series of pins P. In FIG. 1 the pins are shown out of line at their pointed ends, which occurs when inserted by percussion according to existing practice. In FIG. 2 the pins are not an interference fit and have been aligned in accordance with the invention, being held in position within their respective holes within the matrix M by fixing material F. It is a simple matter to align the pins P by means, e.g., of a straight edge E which is positioned opposite the row of pins. In practice the pins are inserted in their respective rows in a stave bar or other matrix and having been aligned the fixing agent is applied to one or both surfaces of the matrix and run into the holes, heat, if necessary, being such as to set or fix the fixing agent.

Referring to FIG. 3, in which pins are aligned at their base ends with the matrix face, the resultant profile is such as would be produced when using the traditional percussion method of fixing pins into a matrix. It is consequent that any irregularity in the taper of the pin or bell-mouthing of the hole will leave an annular space which will grip the passing fibers and thereby cause ringing. However, by alignment of the pins P and the addition of the fixing agent F to the root area in accordance with this invention, there is produced a smooth surface of the matrix at the base of the pins as shown at S in FIG. 4 to the exclusion of the fault previously described. This is particularly important where the surface of the matrix is curved or in the case of pins which are inserted at acute angles.

FIGS. 5 and 6 illustrate that it is possible by controlling the amount or thickness of the fill-in agent F to modify or control the profile of the pin. As clearly seen in FIG 6, the fill-in material has been given a curved profile C. In contrast, in FIG. 5 three different types of pin which are a friction drive-in fit may not subtend the same angle at the point indicated by arrow L which may vary considerably.

In FIG. 7 the invention is shown applied to a knockout type pin wherein H indicates a hammer or punch for the removal of the pins. In FIG. 7 the pins P have a tail R of reduced cross-section but as shown in chain lines in FIG. 7, the pins may be of uniform section throughout. It has also proved possible to build up conventional pins having a parallel shank in such a manner that the fixing agent F adheres to the pin and creates a knock-out shape (see FIG. 7). Even in the case of the pin held without any protruding tall as shown in FIG. 8, its removal can be facilitated by arranging that the grip of the pin to the matrix, i.e., the bond between the fixing agent and the matrix, is only sufficient to maintain it in position during working.

By inserting the pins in the cylinder of a rotary carding or metering machine it has the advantage that not only can the pins be accurately set in position but the pins density can be increased and, furthermore, the pin arrangement can be completely uniform or, when required, have a selected or so-called random pattern of the pin length measured from pin point to base along the row of pins or of the pin angles.

It will be found that by arranging for a random overall pattern of the pin points with respect to the surface of the matrix and more especially in rotary matrices as used in machinery for the fibrillation of thermoplastic films there is a marked improvement in the slitting action of the pins. Any tendency of the film or fiber strip to lift is reduced if not eliminated and penetration is improved giving a more uniform slitting which is marked at high speeds of the film or strip.

The cylinder, which may be open at each end, is mounted for rotation on bearings at each end or by means of end plates to which it is releasably secured, the end plates in turn being mounted in or on suitable supporting bearings.

Referring now to FIGS 9 and 10, the carding element comprises a cylinder C which is open at each end and in which are bores B for the pins P. It will be understood that the bores B may be arranged in parallel rows, pins in adjacent rows being in staggered formation as required.

FIG. 9 shows an alternative arrangement wherein the cylinder C is formed at each end with a counterbore J for engagement with a disc or flange K fast on a spindle A. It will be understood that by detachably connecting the cylinder C to its end plate or disc D, the cylinder can be removed for the purpose of re-pinning.

Provision may be made for interchangeability of an ended spigot piece forming part of a headstock W. End plate D' has a similar but larger aperture G in which is engaged a flanged driving frusto-conical adaptor 0, drive being imparted to the cylinder via pins N on the flange thereof engaging slots in the end plate D By interference fit pinning, the force required to drive or knock pins of the same nominal diameter from the many holes in a pinned article varies enormously. By using a fixing agent, the force required to remove any pin can be predetermined and can be maintained accurately, which is of material importance as one of the major costs in re-pinning is the removal of a fairly small percentage of pins which have become jammed in the hole, and which often break over or burred furred As the fixing agent the product sold under the Trademark LOCTITE has been found to be most suitable, but any of the epoxy resins (i.e. CIBA ARALDITE) or even an adhesive such as SECOTINE could be used. It has been stated that pins are a clearance fit in their holes; experiments have indicated that the hole should be approximately 10 percent larger in diameter than the pin. This, however, is also governed by the depth of the hole relative to the diameter.

It will be understood that the invention is applicable to the pinning of thin in addition to thick-walled metallic and non-metallic tubes without the associated problems of distortion as described earlier, affording a high degree of pin-point positional accuracy when using sharp or blunt pointed pins.

The absence of percussion as applied to the pins eliminates the necessity for designing heavy and detachable matrices. The tubular concept gives licence for the provision of integrated design, ease of removal from the machine and the reduction in dead weight of the pinned roller. The overall result is the opportunity to re-appraise the design of the machine as a whole and the roller in particular.

The method of pin insertion of this invention eliminates distortion of the matrix with the consequent achievement of high pin point positional accuracy when inserting card, hackle, faller, comb pins, rag teeth, staples and/or pins of any cross-sectional shape.

Furthermore, because the surface of the cylinder or tube is continuous circumferentially (and no longer divided into narrow longitudinal slats) it is possible to achieve a truly random pattern of pin point location by sinuating or otherwise irregular drilling of the rows of holes in such a way that successive rows are no longer parallel to each other. The distance between adjacent pins in a row can also be made irregular and as the pins are in the first instance inserted as a loose fit in the drilled hole, the pin axis can be allowed to deviate from the true axial direction of the hole within controlled limits thus achieving a truly random pattern of pin points in a radial circumferential and/or lateral directions relative to the rollers while at the same time retaining a uniform density of points per unit area.

What is claimed is:

1. In a carding, fibrillating or other fiber drawing machine having a pinned matrix such as a cylinder or faller bar the improved method of pinning said matrix comprising the steps of:

i. forming holes in thematrix, the diameter of which holes exceeds by a predetermined amount that of the pins to be inserted therein;

ii. inserting pins having preselected ends in the holes and thereafter aligning them in endwise relation so that their preselected ends are arranged in a predetermined array, and

iii. releasably bonding the pins in position by means of a filling agent.

2. The method of claim 1 wherein said filling agent and each pin are removable from the matrix as a unit.

3. In a carding, fibrillating or other fiber drawing machine having a pinned matrix such as a cylinder or faller bar the improved method of pinning said matrix and replacing pins thereof comprising the steps of:

i. forming holes in the matrix, the diameter of which holes exceeds by a predetermined amount that of the pins to be inserted therein;

ii. inserting pins having preselected ends in the holes and thereafter aligning them in endwise relation so that their preselected ends are arranged in a predetermined array,

iii. releasably bonding the pins in position by means I of a filling agent,

iv. endwise forcing from the matrix each pin to be replaced together with the filling agent,

v. placing a new pin in the hole from which the pin and bonding agent have been removed,

vi. accurately positioning the new pin in the hole, and

vii. releasably bonding the new pin in position by means of additional filling agent.

4. The method as defined in claim 1 wherein the aligning step is performed by engaging ends of said pins projecting outwardly of said holes with template means.

5. The method as defined in claim 4 wherein said template means is a linear straight edge.

6. The method as defined in claim 4 wherein said template means includes a curved edge.

III 

2. The method of claim 1 wherein said filling agent and each pin are removable from the matrix as a unit.
 3. In a carding, fibrillating or other fiber drawing machine having a pinned matrix such as a cylinder or faller bar the improved method of pinning said matrix and replacing pins thereof comprising the steps of: i. forming holes in the matrix, the diameter of which holes exceeds by a predetermined amount that of the pins to be inserted therein; ii. inserting pins having preselected ends in the holes and thereafter aligning them in endwise relatioN so that their preselected ends are arranged in a predetermined array, iii. releasably bonding the pins in position by means of a filling agent, iv. endwise forcing from the matrix each pin to be replaced together with the filling agent, v. placing a new pin in the hole from which the pin and bonding agent have been removed, vi. accurately positioning the new pin in the hole, and vii. releasably bonding the new pin in position by means of additional filling agent.
 4. The method as defined in claim 1 wherein the aligning step is performed by engaging ends of said pins projecting outwardly of said holes with template means.
 5. The method as defined in claim 4 wherein said template means is a linear straight edge.
 6. The method as defined in claim 4 wherein said template means includes a curved edge. 